Neural dynamics during moral persuasion process: an EEG hyperscanning study

Moral persuasion represents a complex form of social cognition, requiring the dynamic integration of moral reasoning, emotional regulation, attentional control, and interpersonal alignment across interacting individuals. This study investigated phase-specific neural alignment to examine how cognitive, emotional, and regulatory processes become coordinated across individuals during a dyadic moral persuasion speech interaction, using electroencephalography (EEG) hyperscanning. Fourteen same-gender dyads engaged in a structured, four-phase dialogue about a moral dilemma. Inter-brain dynamics were assessed using the Euclidean-distance of power spectral density across five EEG bands and three cortical regions (frontal, temporo-parietal, parieto-occipital). Results revealed greater inter-brain dissimilarity in frontal regions compared to posterior areas, particularly in the delta and gamma bands, suggesting differentiated regulatory and evaluative processes between participants. Furthermore, alpha-band dissimilarity varied significantly across discourse phases: divergence was higher during the persuadee's perspective disclosure phase (PPD), while convergence increased during the final conclusion phase (FCP). This pattern may suggest an initial divergent cognitive processing followed by increased neural alignment toward resolution. By revealing region-specific patterns of inter-brain divergence and convergence, this study provides initial insights into the understanding of how neural dynamics support role- and phase-dependent cognitive and regulatory processes during moral persuasion.